Page 89 - The Combined Finite-Discrete Element Method
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72 PROCESSING OF CONTACT INTERACTION
h
4 3
x
1 2
Figure 2.45 Contact force potential specified at nodes of a regular grid.
calculated using local coordinates:
ϕ(ξ, η) = N 1 (ξ, η)ϕ 1 + N 2 (ξ, η)ϕ 2 + N 3 (ξ, η)ϕ 3 + N 4 (ξ, η)ϕ 4 (2.65)
where shape functions are given by
1
N i (ξ, η) = (1 + ξξ i )(1 + ηη i ); i = 1, 2, 3, 4 (2.66)
4
ξ 1 = ξ 4 =−1; ξ 2 = ξ 3 = 1;
η 1 = η 2 =−1; η 3 = η 4 = 1.
